The US advise and assist mission, which works alongside Afghan troops, also operates from the base but in a separate area of the complex. The US and international forces present at the base were safe as the Taliban could not breach the walls of their compound, according to security officials.

Repeated raids

Clashes between the Taliban and the government troops backed by foreign forces have not subsided even as the US and Taliban are holding talks in Qatar to seek a negotiated solution to end Afghanistan's long war.

Afghan forces are taking heavy casualties on the battlefield. President Ashraf Ghani said in January that 45,000 members of the country's security forces have been killed since he became the leader in September 2014.

Repeated raids on Camp Shorab, a sprawling base situated on what used to be Camp Bastion, the former British airbase, and Camp Leatherneck, the old US Marine Corps base in Helmand, have underlined the Taliban's ability to target critical security installations.

The Taliban said its fighters were engaged in clashes with the US and Afghan forces at Shorab base.

"Heavy clashes continue as tens of members of the enemy forces had been killed or were wounded," Qari Yousuf Ahmadi, a Taliban spokesman, said in a statement.

President Donald Trump has said he plans to reduce US forces as talks with the Taliban progress.

In addition to 14,000 Americans, some 8,000 troops from 38 other countries in NATO's Resolute Support mission provide training and support for Afghan forces.

The Taliban controls large areas of Helmand. The province is a source of much of the world's illegal opium supply. During more than a decade of international intervention, it was the deadliest province for foreign troops, claiming nearly 1,000 lives.